Switching amplifier using inductor current feedback

ABSTRACT

A switching amplifying method or a switching amplifier for obtaining a linearly amplified replica of an input signal, is highly efficient, and does not have the disadvantage of “dead time” problem related to the class D amplifiers. Said switching amplifier comprises: an inductor means; a switching unit for switching a current from a DC voltage to the inductor means; a controllable diodes unit for blocking a current when the current from the DC voltage to the inductor means is switched on, and conducting the current from the inductor means to a filter unit when the current from the DC voltage to the inductor means is switched off; an amplifier control unit to control the switching unit and the controllable diodes unit according to the input signal and the current of the inductor means; the filter unit to filter the current from the inductor means to get an output signal.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

This invention is related in general to a power amplifier, and moreparticularly, to a switching amplifier that can efficiently and linearlyamplify an input signal having first and second polarities for obtaininga low-distortion output signal.

(2) Description of the Related Art

Amplifiers are electronic devices which are used for increasing thepower of a signal, and are generally categorized into various classes.The popular amplifiers include class A, class B and class D amplifiers.Reference is made to the exemplary U.S. patents that disclose varioustypes of amplifiers: U.S. Pat. Nos. 7,952,426; 7,816,985; 7,400,191;7,286,008; 6,922,101; 6,794,932; 6,563,377; 6,356,151; 6,282,747;5,949,282; 5,805,020; 5,767,740; 5,160,896; 5,115,205; 5,014,016;4,531,096 and 3,629,616.

In general, class A amplifiers produce a linearly amplified replica ofan input signal, but are inefficient in terms of power usage because theamplifying elements are always biased and conducting, even if there isno input.

Class B amplifiers only amplify half of the input wave cycle, thuscreating a large amount of distortion, but their efficiency is greatlyimproved and is much better than class A. A practical circuit usingclass B elements is the push-pull stage, such as the very simplifiedcomplementary pair arrangement. Complementary or quasi-complementarydevices are each used for amplifying the opposite halves of the inputsignal, which is then recombined at the output. This arrangement givesexcellent efficiency, but can suffer from the drawback that there is asmall mismatch in the cross-over region—at the “joins” between the twohalves of the signal, as one output device has to take over supplyingpower exactly as the other finishes. This is called crossoverdistortion.

In a class D amplifier an input signal is converted to a sequence ofhigher voltage output pulses. The averaged-over-time power values ofthese pulses are directly proportional to the instantaneous amplitude ofthe input signal. The frequency of the output pulses is typically ten ormore times the highest frequency in the input signal to be amplified.The output pulses contain inaccurate spectral components (that is, thepulse frequency and its harmonics) which must be removed by a low-passpassive filter. The resulting filtered signal is then a linearlyamplified replica of the input.

The main advantage of a class D amplifier is power efficiency. Becausethe output pulses have fixed amplitude, the switching elements areswitched either completely on or completely off, rather than operated inlinear mode.

However, one significant challenge for a driver circuit in class Damplifiers is keeping dead times as short as possible. “Dead time” isthe period during a switching transition when both output MOSFETs aredriven into Cut-Off Mode and both are “off”. Dead times need to be asshort as possible to maintain an accurate low-distortion output signal,but dead times that are too short cause the MOSFET that is switching onto start conducting before the MOSFET that is switching off has stoppedconducting. The MOSFETs effectively short the output power supplythrough themselves, a condition known as “shoot-through”. Driverfailures that allow shoot-through result in excessive losses andsometimes catastrophic failure of the MOSFETs.

Therefore, the main disadvantage of a class D amplifier is having the“dead time” problem to cause the distortion of the output signal.

In summary, class A amplifiers produce a linearly amplified replica ofan input signal, but are inefficient in terms of power usage. Thepush-pull class B amplifiers provide excellent efficiency (compared toclass A amplifiers), but introduce crossover distortion. Class Damplifiers are most efficient compared to class A and class Bamplifiers, but there is one significant problem for MOSFET drivercircuits in class D amplifiers: the “dead time” that cause thedistortion of the output signal.

Accordingly, in light of current state of the art and the drawbacks tocurrent amplifiers mentioned above. A need exits for a switchingamplifier that would continue to be highly efficient, that wouldefficiently and linearly amplify an input signal for generatinglow-distortion output signals.

SUMMARY OF THE INVENTION

The present invention discloses a switching amplifier that produces alinearly amplified replica of an input signal, is highly efficient, anddoes not have the “dead time” problem related to class D amplifiers.

One aspect of the present invention provides a method of obtaining anoutput signal from a direct current (DC) voltage, wherein the outputsignal is a linearly amplified replica of an input signal having firstand second polarities, comprising the steps of: receiving the inputsignal; transforming the input signal for generating a discrete timepeak current signal, wherein said transforming is according to that whenapplying the direct current (DC) voltage to an inductor means, theenergy stored in the inductor means is proportional to the square of thepeak current of the inductor means; switching a current from the directcurrent (DC) voltage to the inductor means and getting a feedbackcurrent signal by detecting the current of the inductor means, whereinsaid switching is according to the discrete time peak current signal andthe feedback current signal; blocking a current from the inductor meansto a filter when the current from the direct current (DC) voltage to theinductor means is switched on and conducting the current from theinductor means to the filter when the current from the direct current(DC) voltage to the inductor means is switched off; filtering saidcurrent from the inductor means for outputting the output signal by thefilter.

Yet another aspect of the present invention provides a switchingamplifier further comprising a negative feedback signal generator togenerate a negative feedback signal corresponding to the output signal,wherein the amplifier control unit integrates the input signal and thenegative feedback signal to process a negative feedback control.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages of the present generalinventive concept will become more apparent by describing in detailexemplary embodiments thereof with reference to the attached drawings inwhich:

FIG. 1 is an exemplary block and circuit diagram illustrating anembodiment of a switching amplifier in accordance with the presentinvention, wherein the switching amplifier has switches configured as afull bridge topology.

FIG. 2 is an exemplary block and circuit diagram illustrating anembodiment of the amplifier control unit integrating an input signal anda negative feedback signal in FIGS. 1, 3 and 4 in accordance with thepresent invention.

FIG. 3 is an exemplary block and circuit diagram illustrating anembodiment of a switching amplifier in accordance with the presentinvention, wherein the switching amplifier has switches configured as ahalf bridge topology.

FIG. 4 is an exemplary block and circuit diagram illustrating anembodiment of a switching amplifier in accordance with the presentinvention, wherein the switching amplifier has switches configured as apush pull topology.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The detailed description set forth below in connection with the appendeddrawings is intended as a description of presently preferred embodimentsof the invention and is not intended to represent the only forms inwhich the present invention may be constructed and or utilized.

FIG. 1 is an exemplary block and circuit diagram illustrating anembodiment of a switching amplifier 100 in accordance with the presentinvention, wherein the switching amplifier 100 having switches 102A,102B, 102C and 102D configured as a full bridge topology.

As illustrated in FIG. 1, the switching amplifier 100 of the presentinvention for amplifying an input signal 106 having positive andnegative polarities is comprised of: an inductor means 101; a switchingunit 102 comprising four switches 102A, 102B, 102C and 102D configuredas a full bridge topology for switching a current from a direct current(DC) voltage 103 to the inductor means 101; a controllable diodes unit104 comprising two switches 104A, 104B and two diodes 104C, 104D; anegative feedback current signal generator 113 to generate a negativefeedback current signal 114 corresponding to the current of the inductormeans 101; an amplifier control unit 105 for receiving the input signal106 and coupled to the switches 102A, 102B, 102C and 102D of theswitching unit 102 and the switches 104A and 104B of the controllablediodes unit 104 for controlling their switching; a filter unit 107coupled to the controllable diodes unit 104 and outputting the outputsignal 108.

In this non-limiting exemplary embodiment, the input signal 106 is ananalog signal. And it is obvious for a corresponding embodiment of aswitching amplifier in accordance with this invention if the inputsignal is a discrete time signal.

As further illustrated in FIG. 1, the inductor means 101 is an inductoroperated in discontinuous mode. Accordingly, when the current from thedirect current (DC) voltage 103 to the inductor means 101 is switchedon, the current from the inductor means 101 to the filter unit 107 isblocked by the controllable diodes unit 104. Therefore, during thisswitched on period, the current in the inductor means 101 builds uplinearly in it from zero to a peak value.

Further, when the current from the direct current (DC) voltage 103 tothe inductor means 101 is switched off, the current from the inductormeans 101 to the filter unit 107 is conducted by the controllable diodesunit 104 for delivering energy in the inductor means 101 to the filterunit 107.

Therefore, during the period when the current from the direct current(DC) voltage 103 to the inductor means 101 is switched on, the directcurrent (DC) voltage 103 is applied across the inductor means 101, andthe current in the inductor means 101 builds up linearly from zero to apeak value. During the switched on period, the energy stored in theinductor means 101 is according to the equation:

$E = \frac{{L_{p}\left( I_{p} \right)}^{2}}{2}$wherein E is the energy stored, L_(p) is the inductance of the inductormeans 101, and I_(p) is the peak value of the current in the inductormeans 101 at the end of the switched on period. Therefore, the energystored into the inductor means 101 during a switched on period isdetermined by the inductance of the inductor means 101 and the peakvalue of the current in the inductor means 101 at the end of theswitched on period.

As further illustrated in FIG. 1, the amplifier control unit 105comprises:

An input unit 105A for receiving the input signal 106 and having ananalog to digital converter for converting the input signal 106 to adiscrete time input signal x[n]x={x[n]},0<n<∞;wherein the sampling frequency of the discrete time input signal x[n] isaccording to the switching frequency of the switching unit 102 and thecontrollable diodes unit 104, therefore, each x[n] is corresponding toinstantaneous amplitude of the input signal which corresponding toenergy to be delivered at each switching.

A signal processing unit 105B for transforming the discrete time inputsignal x[n] to a discrete time peak current signal I_(p)[n] according tothe followings:

$\begin{matrix}{{I_{p}\lbrack n\rbrack} = {\sqrt[2]{\frac{x\lbrack n\rbrack}{x_{\max}}} \times I_{pmax}}} & {{0 < n < \infty};}\end{matrix}$wherein x_(max) is the maximum value of the discrete time input signaland I_(pmax) is the maximum value of peak current in the inductor means101 at the end of the switched on period corresponding to x_(max),wherein the x_(max) and I_(pmax) are all design parameters of theswitching amplifier 100. Since the input signal 106 has first and secondpolarities, therefore, the discrete time peak current signal I_(p)[n]also has first and second polarities.

A switching control unit 105C coupled to the switches 102A, 102B, 102Cand 102D of the switching unit 102 and the switches 104A and 104B of thecontrollable diodes unit 104 to control their switching according to thediscrete time peak current signal I_(p)[n] and the negative feedbackcurrent signal 114 corresponding to the current through the inductormeans 101. When the input signal 106 is zero, the switches 102A, 102B,102C and 102D of the switching unit 102 and the switches 104A and 104Bof the controllable diodes unit 104 are all switched off. When the inputsignal 106 is not zero, the switches 102A, 102B, 102C and 102D switchthe current from the direct current (DC) voltage 103 to the inductormeans 101 according to the discrete time peak current signal I_(p)[n]and the negative feedback current signal 114, for example, at start ofeach switching, for that the polarity of I_(p)[n] is positive thereforethe switch 104A is switched on and the switch 104B is switched off, theswitching control unit 105C switches on the switches 102A, 102C andcompares the discrete time peak current signal I_(p)[n] to the negativefeedback current signal 114.

When the negative feedback current signal 114 reaches I_(p)[n], theswitching control unit 105C switches off the switch 102A, 102C and waitsfor next switching start. For that the polarity of I_(p)[n] is negativetherefore the switch 104A is switched off and the switch 104B isswitched on, the switching control unit 105C switches the switches 102B,102D according to the discrete time peak current signal I_(p)[n] and thenegative feedback current signal 114, respectively.

As further illustrated in FIG. 1, the filter unit 107 is a low passfilter to obtain the output signal 108 corresponding to the input signal106 by filtering the output of the controllable diodes unit 104 andoutputting the output signal 108.

As illustrated in FIG. 1, the diodes 104C, 104D can be replaced byswitches respectively for better power efficiency. Further, it isobvious that the switch 104A and the diode 104C can be configured into asole switch, the switch 104A and the diode 104C can be configured into asole switch, either. Furthermore, the controllable diodes unit 104 canbe implemented by a solid state relay, a switch that can switch off analternating current, with fast enough switching speed, although theswitching would be a little more complicate.

As further illustrated in FIG. 1, the switching amplifier 100 furthercomprises a negative feedback signal generator 111 to generate anegative feedback signal corresponding to the output signal 112, whereinthe amplifier control unit 105 integrates the input signal 106 and thenegative feedback signal 112.

FIG. 2 is an exemplary block and circuit diagram illustrating anembodiment of the amplifier control unit 105 integrating the inputsignal 106 and a negative feedback signal 112 in FIGS. 1, 3 and 4 inaccordance with the present invention.

As illustrated in FIG. 2 and FIG. 1, the input unit 105A has an analogto digital converter 201 and further comprises a linear digitaltransformer 202 and a negative feedback controller 203. Wherein theanalog to digital converter 201 receives the input signal 106 andconverts the input signal 106 to a discrete time input signal x[n]:x={x[n]},0<n<∞;

The linear digital transformer 202 transforms the discrete time inputsignal x[n] by multiplying a gain G to the discrete time input signalx[n] (the default value of the gain G is 1):Y[n]={G×x[n]},0<n<∞to get a compensated discrete time signal Y[n] and sends the compensateddiscrete time signal Y[n] to the signal processing unit 105B.

Accordingly, for the switching amplifier 100 which further comprises thenegative feedback signal generator 111 to generate the negative feedbacksignal 112 corresponding to the output signal 108 and the amplifiercontrol unit 105 further integrating the negative feedback signal 112,the signal processing unit 105B receives the compensated discrete timesignal Y[n], and the output of the signal processing unit 105B is:

$\begin{matrix}{{I_{p}\lbrack n\rbrack} = {\sqrt[2]{\frac{Y\lbrack n\rbrack}{x_{\max}}} \times I_{pmax}}} & {{0 < n < \infty};}\end{matrix}$As further illustrated in FIG. 2, the negative feedback controller 203receives the discrete time input signal from the analog to digitalconverter 201 and compares it to the negative feedback signal 112,therefore to adjust the gain G of the linear digital transformer 202according to the comparison. For example, if the negative feedbacksignal 112 corresponding to the output signal 108 shows that the outputsignal 108 is below a required level, then the negative feedbackcontroller 203 will increase the gain G of the linear digitaltransformer 202 to increase the output signal 108, wherein said requiredlevel is obtained according to the discrete time input signal.

FIG. 3 is an exemplary block and circuit diagram illustrating anembodiment of a switching amplifier 300 in accordance with the presentinvention, wherein the switching amplifier 300 having switches 302A and302B configured as a half bridge topology.

As illustrated in FIG. 3, the switching amplifier 300 of the presentinvention for amplifying an input signal 106 having positive andnegative polarities is comprised of: an inductor means 101; a switchingunit 302 comprising two switches 302A and 302B configured as a halfbridge topology coupled to the inductor means 101 for switching acurrent from a direct current (DC) voltage 103 to the inductor means101; a controllable diodes unit 104 comprising two switches 104A, 104Band two diodes 104C, 104D coupled to inductor means 101; a negativefeedback current signal generator 113 to generate a negative feedbackcurrent signal 114 corresponding to the current of the inductor means101; an amplifier control unit 105 for receiving the input signal 106and coupled to the switches 302A and 302B of the switching unit 302 andthe switches 104A and 104B of the controllable diodes unit 104 forcontrolling their switching; a filter unit 107 coupled to thecontrollable diodes unit 104.

In this non-limiting exemplary embodiment, the input signal 106 is ananalog signal. However, a corresponding embodiment of a switchingamplifier in accordance with this invention for an input signal which isa discrete time signal is obvious.

As further illustrated in FIG. 3, the inductor means 101 is an inductor.Accordingly, when the current from the direct current (DC) voltage 103to the inductor means 101 is switched on by the switching unit 302, thecurrent from the inductor means 101 to the filter unit 107 is blocked bythe controllable diodes unit 104. Therefore, during this switched onperiod, the current through the inductor means 101 builds up linearlyfrom zero to a peak value.

Further, when the current from the direct current (DC) voltage 103 tothe inductor means 101 is switched off, the current from the inductormeans 101 to the filter unit 107 is conducted by the controllable diodesunit 104 for delivering energy in the inductor means 101 to the filterunit 107.

As further illustrated in FIG. 3, the amplifier control unit 105comprises an input unit 105A for receiving the input signal 106 andconverting the input signal 106 to a discrete time input signal x[n],wherein the sampling frequency of the discrete time input signal x[n] isaccording to the switching frequency of the switching unit 302 andcontrollable diodes unit 104; a signal processing unit 105B fortransforming the discrete time input signal and outputting a discretetime peak current signal I_(p)[n], as previously illustrated in FIG. 1;and a switching control unit 105C coupled to the switches 302A and 302Bof the switching unit 302 and the switches 104A and 1048 of thecontrollable diodes unit 104 to control their switching.

As illustrated in FIG. 3, the switching control unit 105C coupled to theswitches 302A and 302B of the switching unit 302 and the switches 104Aand 104B of the controllable diodes unit 104 to control their switchingaccording to the discrete time peak current signal I_(p)[n] and anegative feedback current signal 114 corresponding to the current in theinductor means 101. When the input signal 106 is zero, the switches 302Aand 302B of the switching unit 302 and the switches 104A and 1048 of thecontrollable diodes unit 104 are all switched off. When the input signal106 is not zero, the switches 302A and 302B switch the current from thedirect current (DC) voltage 103 to the inductor means 101 according tothe discrete time peak current signal I_(p)[n] and the negative feedbackcurrent signal 114, for example, at start of each switching, for thatthe polarity of I_(p)[n] is positive therefore the switch 104A isswitched on and the switch 1048 is switched off, the switching controlunit 105C switches on the switch 302A and compares the discrete timepeak current signal I_(p)[n] to the negative feedback current signal114. When the negative feedback current signal 114 reaches I_(p)[n], theswitching control unit 105C switches off the switch 302A and waits fornext switching start. For that the polarity of I_(p)[n] is negativetherefore the switch 104A is switched off and the switch 104B isswitched on, the switching control unit 105C switches the switches 302Baccording to the discrete time peak current signal I_(p)[n] and thenegative feedback current signal 114, respectively.

As further illustrated in FIG. 3, the filter unit 107 is a low passfilter to obtain the output signal 108 corresponding to the input signal106 by filtering the output of the controllable diodes unit 104 andoutputting the output signal 108.

As further illustrated in FIG. 3, the switching amplifier 300 furthercomprises a negative feedback signal generator 111 to generate anegative feedback signal corresponding to the output signal 112, whereinthe amplifier control unit 105 integrates the input signal 106 and thenegative feedback signal 112.

FIG. 4 is an exemplary block and circuit diagram illustrating anembodiment of a switching amplifier 400 in accordance with the presentinvention, wherein the switching amplifier 400 has switches 402A and402B configured as a push pull topology.

As illustrated in FIG. 4, the switching amplifier 400 of the presentinvention for amplifying an input signal 106 having positive andnegative polarities is comprised of: an inductor means 401; a switchingunit 402 comprising two switches 402A and 402B configured as a push pulltopology and coupled to the inductor means 501 for switching a currentfrom a direct current (DC) voltage 103 to the inductor means 501; adiode 402C for preventing a current flow from the inductor means 401 tothe direct current (DC) voltage 103; a controllable diodes unit 104comprising two switches 104A, 104B and two diodes 104C, 104D coupled tothe inductor means 401; a negative feedback current signal generator 113to generate a negative feedback current signal 114 corresponding to thecurrent of the inductor means 401; an amplifier control unit 105 forreceiving the input signal 106 and coupled to the switches 402A and 402Bof the switching unit 402 and the switches 104A and 1048 of thecontrollable diodes unit 104 for controlling their switching; a filterunit 107 coupled to the controllable diodes unit 104.

In this non-limiting exemplary embodiment, the input signal 106 is ananalog signal. However, a corresponding embodiment of a switchingamplifier in accordance with this invention for an input signal which isa discrete time signal is obvious.

As further illustrated in FIG. 4, the inductor means 401 is an inductorhaving a center tap. Accordingly, when the current from the directcurrent (DC) voltage 103 to the inductor means 401 is switched on by theswitching unit 402, the current from the inductor means 401 to thefilter unit 107 is blocked by the controllable diodes unit 104.Therefore, during this switched on period, the current through theinductor means 401 builds up linearly from zero to a peak value.

Further, when the current from the direct current (DC) voltage 103 tothe inductor means 401 is switched off, the current from the inductormeans 401 to the filter unit 107 is conducted by the controllable diodesunit 104 for delivering energy in the inductor means 401 to the filterunit 107.

As further illustrated in FIG. 4, the amplifier control unit 105comprises an input unit 105A for receiving the input signal 106 andconverting the input signal 106 to a discrete time input signal, whereinthe sampling frequency of the discrete time input signal x[n] isaccording to the switching frequency of the switching unit 402 and thecontrollable diodes unit 104; a signal processing unit 105B fortransforming the discrete time input signal and outputting a discretetime peak current signal I_(p)[n], as previously illustrated in FIG. 1;and a switching control unit 105C coupled to the switches 402A and 402Bof the switching unit 402 and the switches 104A and 1048 of thecontrollable diodes unit 104 to control their switching.

As illustrated in FIG. 4, the switching control unit 105C coupled to theswitches 402A and 402B of the switching unit 402 and the switches 104Aand 104B of the controllable diodes unit 104 to control their switchingaccording to the discrete time peak current signal I_(p)[n] and thenegative feedback current signal 114 corresponding to the current in theinductor means 401. When the input signal 106 is zero, the switches 402Aand 402B of the switching unit 402 and the switches 104A and 1048 of thecontrollable diodes unit 104 are all switched off. When the input signal106 is not zero, the switches 402A and 402B switch the current from thedirect current (DC) voltage 103 to the inductor means 401 according tothe discrete time peak current signal I_(p)[n] and the negative feedbackcurrent signal 114, for example, at start of each switching, for thatthe polarity of I_(p)[n] is positive therefore the switch 104A isswitched on and the switch 1048 is switched off, the switching controlunit 105C switches on the switch 402A and compares the discrete timepeak current signal I_(p)[n] to the negative feedback current signal114. When the negative feedback current signal 114 reaches I_(p)[n], theswitching control unit 105C switches off the switch 402A and waits fornext switching start. For that the polarity of I_(p)[n] is negativetherefore the switch 104A is switched off and the switch 104B isswitched on, the switching control unit 105C switches the switch 402Baccording to the discrete time peak current signal I_(p)[n] and thenegative feedback current signal 114 corresponding to the current in theinductor 401, respectively.

As further illustrated in FIG. 4, the filter unit 107 is a low passfilter to obtain the output signal 108 corresponding to the input signal106 by filtering the output of the controllable diodes unit 104 andoutputting the output signal 108.

As further illustrated in FIG. 4, the switching amplifier 400 furthercomprises a negative feedback signal generator 111 to generate anegative feedback signal corresponding to the output signal 112, whereinthe amplifier control unit 105 integrates the input signal 106 and thenegative feedback signal 112.

From the switching amplifiers 100, 300 and 400 in accordance with thepresent invention, one aspect of the present invention provides aswitching amplifier that is highly efficient and without the “dead time”problem related to the class D amplifiers. Accordingly, the switches ofthe switching amplifiers 100, 300 and 400 are never short the directcurrent (DC) voltage 103 through themselves.

From the switching amplifiers 100, 300 and 400 in accordance with thepresent invention, another aspect of the present invention provides aswitching amplifier that is completely off when there is no inputsignal, as illustrated in FIG. 2.

From the switching amplifiers 100, 300 and 400 in accordance with thepresent invention, yet another aspect of the present invention providesa switching amplifier comprised of an act of comparing an input signalwith an output feedback signal for detection and correction of overallsystem signal processes therefore does not require a power supplyregulator and is substantially immune to power supply and loadperturbations, as illustrated in FIGS. 1, 2, 3 and 4.

It is to be understood that the above described embodiments are merelyillustrative of the principles of the invention and that otherarrangements may be devised by those skilled in the art withoutdeparting from the spirit and scope of the invention.

What is claimed is:
 1. A method of obtaining an output signal from adirect current (DC) voltage, wherein the output signal is a linearlyamplified replica of an input signal having first and second polarities,comprising the steps of: receiving the input signal; transforming theinput signal for generating a discrete time peak current signal, whereinsaid transforming is according to that when applying the direct current(DC) voltage to an inductor means, the energy stored in the inductormeans is proportional to square of the peak current of the inductormeans; switching a current from the direct current (DC) voltage to theinductor means and getting a feedback current signal by detecting thecurrent of the inductor means, wherein said switching is according tothe discrete time peak current signal and the feedback current signal;blocking a current from the inductor means to a filter when the currentfrom the direct current (DC) voltage to the inductor means is switchedon and conducting the current from the inductor means to the filter whenthe current from the direct current (DC) voltage to the inductor meansis switched off; filtering said current from the inductor means foroutputting the output signal by the filter.
 2. The method of claim 1further comprising: getting a feedback signal by detecting the outputsignal and integrating the feedback signal to process a negativefeedback control.
 3. A switching amplifier for amplifying an inputsignal having first and second polarities, said amplifier comprising: aninductor means; a switching unit coupled to the inductor means forswitching a current from a direct current (DC) voltage to the inductormeans; a controllable diodes unit coupled between the inductor means anda filter unit for blocking a current from the inductor means to thefilter unit when the current from the direct current (DC) voltage to theinductor means is switched on by the switching unit, and conducting thecurrent from the inductor means to the filter unit when the current fromthe direct current (DC) voltage to the inductor means is switched off; anegative feedback current signal generator to generate a negativefeedback current signal corresponding to the current of the inductormeans; an amplifier control unit for receiving the input signal, thenegative feedback current signal and coupled to the switching unit andthe controllable diodes unit to control their switching according to theinput signal and the negative feedback current signal; the filter unitto obtain an output signal corresponding to the input signal byfiltering the output of the controllable diodes unit and outputting theoutput signal.
 4. The switching amplifier according to claim 3, furthercomprising: a negative feedback signal generator to generate a negativefeedback signal corresponding to the output signal, wherein theamplifier control unit integrates the input signal and the negativefeedback signal to process a negative feedback control.
 5. The switchingamplifier according to claim 3, wherein the switching unit comprises aplurality of switches configured as a full bridge topology.
 6. Theswitching amplifier according to claim 3, wherein the switching unitcomprises a plurality of switches configured as a half bridge topology.7. The switching amplifier according to claim 3, wherein the switchingunit comprises a plurality of switches configured as a push pulltopology.
 8. The switching amplifier according to claim 3, wherein thecontrollable diodes unit comprises two switches and two diode means. 9.The switching amplifier according to claim 8, wherein the diode means isa diode.
 10. The switching amplifier according to claim 8, wherein thediode means is a synchronous switch.
 11. The switching amplifieraccording to claim 3, wherein the controllable diodes unit comprises twoswitches.
 12. The switching amplifier according to claim 3, wherein thecontrollable diodes unit comprises one switch that can switch off analternating current.
 13. The switching amplifier according to claim 3,wherein the input signal is an analog signal.
 14. The switchingamplifier according to claim 3, wherein the input signal is a discretetime signal.
 15. The switching amplifier according to claim 3, whereinthe filter unit is a low pass filter.
 16. The switching amplifieraccording to claim 3, wherein the filter unit is a band pass filter. 17.The switching amplifier according to claim 3, wherein the filter unit isa band stop filter.